Magnetic alloys



March l2, 1940.

v YAY VAYA MAXIMUM AXXYXVAVAVAVAVPVAVAVAVAVAVA vAviv'mvAAvAvAv l /u) FesL-AL sYsfem PsraMEABmTYC/l m) Filed Sept. 14. 1937 Y. v A A A hummm/10. 96 myvvvvvvv/vnv 97 AY/Annvixv* AVAVAVAVAVVAVAVAVAVA AVAVAVA Fe- Sie AL Sys em 1N1T|AL PERMEABlUTY (Ho) AAVAVA AVAVAVAVAVAVA A INVEN-roRs HAKARU MAsuMoT Y TATsUJl YAMAMo AVAVAVAVAVAVAVAVAVAV ATTORN YS Patented Mar. 12, 1940.

,UNITED STATES MAGNETIC ALLoYs Hakan-u Masumoto and Tatsuji Yamamoto,

Sendai, Japan, assignors to The Kinzoku Zairyo Kenkyusho, Sendai, Japan Application September 14,1937, Serial No. 163,776

Inx

Claims.

This invention relates to magnetic alloys having very high permeability and specific resistance and very low hysteresis loss.v

Many magnetic alloys are known to theprior 5 art, such as iron-silicon alloys and permalloys, which materials have been used as magnetic cores in lvarious electric machines and apparatus such as transformers, loading coils and the like. The best silicon-iron alloy known up to the time of the present invention has contained about 4% of silicon, the remainder being iron.

Although these heretofore known alloys have been used to quite a large extent, they are `not completely suitable for these lpurposes in several of their properties. Furthermore, a magnetic alloy of iron, silicon, aluminum andl optionally also phosphorous is suggested in the prior art, but'the proportions of the ingredients used did not prot/ide products of high quality.

The principal object of the present invention is to' produce alloys for electromagnetic uses which have much higher permeability, greater specific resistance and less hysteresis loss than the alloys heretofore known.

As the result of exhaustive experiments, we have discovered that silicon-aluminum-iron alloys can be produced which have superior magnetic properties ing the above mentioned alloys. These new alloys simple operations. An exceedingly valuable alloy constituting one example of the present invention contains 9.5% of silicon and 4.5% of aluminum, the remainder being iron, which alloy possesses a very high initial permeability and other outstanding properties.

We have furthermore discovered that the proportions of these three metals may be varied considerably from the optimum proportions giving 4:0 the highest. initial permeability characteristics,

and yet obtain alloys having other highly desirable magnetic properties. For example, most of the alloys producible within the ranges of 3.5 to 12% of silicon, 3 to 12% ofA aluminum and 81.5

to 91% of iron have an initial permeability in excess of 1500 mu and also other superior magnetic properties. Alloys of good properties are likewise obtained within the broader ranges of 0.5 to 16% or 2 to 13% of silicon, 0.5 or 2 to 16% of aluminum and not more than 90 or 91% of iron, preferably from 80 to 89%. An increase in the percentages of the non-ferrous metals from these minimums leads to better products. For example, the alloys of silicon in the proportion of 6 or '7 to 11%, of the aluminum in the propor- Ation of 4 to 8 or 9%, the remainder (82 to 38%) being of `iron are excellent.

In producing the alloys of the present invention, the several metals are mixed together in the proper proportions and melted in any suitto those known to the prior art, includmay be manufactured at a low cost through very Japan February 6, 1932 (Cl. 'i5-124) able apparatus as through the use of an induction furnace. 'Ihe molten mass may then be cast in an suitable iron mold. Thereafter, it is heat treated' by an annealing operation at about 1000 C. for a suitable period, as for several hours, and the mass is then allowed to cool slowly in order to develop the required properties.

The excellent properties of two alloys within the scope of the present invention as compared with a most common prior alloy 'may be observed from the following table. The alloy A in the table comprises one which is frequently used for transformers and contains about 4% of silicon. The alloy B, constituting an example of an alloy of the present invention, contains 9.5% of silicon, 4.5% of aluminum and 86% of iron. The alloy C, constituting another example of the present invention, contains 9.5% of silicon, 6% of aluminum and 84.5% of iron. The superiority of the alloys of the present invention may be readily observed from the experimental results as here recorded.

The results recorded in the above table show clearly that the. alloys of the present invention possess a much resistance and have less hysteresis loss than the alloys of the usual iron-silicon composition which have been known up to the present time as the best magnetic material of 'this nature.-

In order to illustrate the superiority of the alloys of the present invention, a drawing is submitted herewith showing diagrams upon which the initial permeabilities (Figure l) and the maximum permeabilities (Figure 2) of the various alloys within the scope of the present invention are recorded. The diagrams reveal the relative eifectiveness of the various proportions of the silicon, aluminum and iron in the alloys with respect to these properties. It should be understood` therefore that the drawing is concerned with only two of thesuperior properties of the present compositions and that other good properties, such as the magnetic induction and the magnetic hysteresis loss, theyresidual magnetic induction, the coercive force, `the magnetic intensity, the specific electric resistance and the average temperature coefficient for electric resistance are not shown. It is believed, however, that the superiority ofthe alle of the present invention is readily appare; from the drawing. From Figure 1 of lthis drawing. it will be noted greater permeability and specic ill',

that alloys of good initial permeability are obtained where. the metals are in the proportions described herein. It will also be observed that alloys of rather high permeability are obtained through the use of over 5% and up to 12% of silicon and from 2 to 10% of aluminum, the

remainder being iron. When the alloy contains est value of 35,100 mu when the silicon consti tutes about 9.62% and the aluminum constitutes 5.38%, the maximum permeability of the alloy being 117,500 m11.

As may be observed from Figure 2, the maximum permeability of the alloys of the present invention containing 6.5% of silicon gradually increases as the aluminum content is increased. A maximum permeability of 54,000 mu is reached when the silicon is at about 5.5% and the aluminum about 3%, the addition of further aluminum causing this value to decrease. When the silicon content is increased and constitutes from 7 to 11% and the aluminum content is from 4 to 8%, the remainder being iron, an extremely high maximum permeability is obtained, the

value reaching 162,000 mu when the alloy contains about 9.66% of silicon and 6.21% of aluminum.

Magnetic materials suitable for electrical may chines and devices require a high permeability and small hysteresis loss and also a high electric specic resistance, vthe latter quality serving the purpose of reducing the change of permeability due to the variation of the eld strength and also to obtain a small eddy current loss. For some purposes the magnetic materials should possess a greater electrical resistance and a smaller variation of permeability at the expense of some reduction of permeability. For these reasons, the alloys of the present invention may be modiiied by the addition of other metals or metalloids which may be added in a quantity amounting to less than as to their total sum. Metals of the nature of nickel, cobalt, chromium, tungsten, molybdenum, manganese, vanadium, titanium, tin and zinc may be added in a quantity not in excess of about 10%. The metals magnesium, antimony, tantalum and beryllium may be added in an amount which should not exceed about 5%. The metals boron, copper and phosphorous may be incorporated in the alloy in quantities not exceeding about 2%. Arsenic, sulfur and zirconium may be used in small amounts. With reference to all of these metals, the quantity used must be nsuiiicient to destroy the herein described magnetic properties of the resulting alloy. The addition of most any of these substances even in small amounts, will result .in an increase in the electric resistance or in less change of permeability for different intensities of 'themagnetic field. The addition of any other element besides the above mentioned metals to the iron-silicon-altiminum alloys of the present invention will generally increase the electric resistance without excessively irnpeding their magnetic properties. Up to 7% of manganese, tin or vanadium, or up to 2% of antimony, or upto 5% arcanes of chromium may be used to produce alloys of special magnetic properties of particular interest in the arts. I

In order to illustrate the effect of the addition of a metal, the following table is recorded from experimental results:

Added elementsi, A] Initial per- Ssfgge' per. .f 'meabil1ty, cent percent Fe, M u mu micro-ohms/ l percent percent cu' cm or dust cores of loading coils used in telephone systems.

The superior magnetic properties of the alloys of the present invention are attributable mainly to the discovery of the most effective proportions of silicon and aluminum content of the siliconaluminum-iron alloys. For example, alloys possessing an initial permeability of a minimum of 2,000 mu may be produced by formation of an alloy containing from 4 to 11% silicon and from 3.5 to 11% aluminum.

The iron employed may satisfactorily be that which is known as electrolytic iron which is substantially free of other metals and of non-metals including carbon.

The alloys of the present invention may be cast or molded into the form of a sheet or they may be crushed into particles or powders in which form they are adapted for use in the production of dust cores of loading coils.

This application is a continuation-in-part of the applicants copending application Serial No.

652,101, led January 16, 1933.

It should be understood that the present invention is not limited to the specic proportions and treatment herein described but that it extends to all equivalents coming within the scope of the appended claims.

We claim:

1. A substantially carbon-free ternary magnetic alloy adapted for use in magnetic parts of electric machines and devices composed of over 5% up to 12% of silicon, 2 to 10% of aluminum and the remainder of iron.

2. A magnetic alloy for electromagnetic pur- Vposes composed of 8.6 to 9.8% of silicon, 5.2 to' 

